X-ray tube.



J. E. SEELEY.

X-RAY TUBE. APPLIS/mon FILED MAR.3I. |913.

Patented July 20, 1915.

.x-RAY TUBE.

Application led March 31, 1913. Serial No. 757,735.

To all whom it may concem:

Be it lmown that IJAMEs E. SEELEY, a citizen ofthe United States, residing at Losl An cles, in the county of Los Angeles, State of alifornia, have -invented new and useful Improvements in X-Ray Tubes, of which the follov'vin'gv is a' specification.

4 Thisinvention relates to a double cathode X-ray tube for use with alternating currents irrespective of their method of production and, especially with alternating high fre `quency currents.

l The present invention consists fundamentally in the combination of a pair of cathodes and a single target, in such 'arrangement that both cathodes may focus on and bombard the target at a single focus point. This invention is efl'ectedby an arrangement of both cathodes on thesame side of ,the plane of the impact face of the target; and the arrangement necessitates relatively angular positions of the cathode axes, these axes in tersectin'g Vat* the, point of impact on the thereof.

target, and also practically necessitates the placement of the target at an angle with the plane determined by the cathode axes. These features, and others of more minor importance, accomplish the fundamental ob-` ject of my invention that object being to provide a tube capable of operating with alternating currents and having a single focus point on the target. A

Specification of Letters Patent.

I win explain in daarin the following specifications, references being had to the accompanying drawings, in whlch:

. Figure 1 is'an elevation of my improved X-ray tube. Fig. 2 is a sectional plan In the drawings `10 may designate a bulb of any suitable size; and I may provide this bulb with any of theattachments commonly used, such as automatic vacuum maintaining appliances and the like. For clarity of illus# trationI have onlyshownherein a-plain bulb with the arts necessary to my inven-l tion. -I provi e a-,pair of elongations'or necksll each 'o fwhichcontains a cathode A12,ftl1e .cathcdesupportsjandconnections 1,3

extending to the ends of the;-necks 11 `and f connecting with :tex-minals-514gg-at `their -extremities;4 .'lhecatliees any suitablegmgnn Igha. ard

.Thezcathvdesf th '9393l 'Ofi 9de" t ereom) ihtersectata eerta1npoint,whic

own-a. standtages-'of mgA The catho es will connect into an alternat- Patented July 20, 19M.

point is the focus point 14 on target 15.

`The cathodes have their discharge faces suitably formed to focus the cathode rays as nearly as possible on the point 14; so that the efect of both cathodes in operation is to forma source of X-rays about the single point 14 of suitably small dimensions to produce concentrated radiation of the vX-rays allld consequently clear effects produced by t em.

lt will be seen that-the cathodes are both placed on oneside of the plane of impact on the target; and the angle between the cathf ode axes and between them and the plane of the target is determined by consideration .of

best production of the X-rays and of their Vunobstructed radiation from the target over a wide field. For instance, it will be seen connection with the minimum obstruction of the. X-rays by the cathodes themselves. In 4the ltube which I have constructed and 'used the angles are approximately those shown in the drawings and I have found this arrangement very effective. But I do not wish to limit myself to this particular speciic design.

The target 15 may be supported, as at 16 by any suitable means and may have a ter minal connection 17, which may be used as a neutral connection. I have shown a simple form of target; a preferred form may be similar to the copper backed target now com monly'- in use. M 'combination does not preclude the use o an anode separate from the target; and, as mentioned hereinbefore, my tube may be supplied with appurtenances and accessories as desired.

` From the foregoingmthe-use and advanf tube will readily understood.v

ing high-'potential circuit with the result that they alternately become cathodes or anodes; and acontinuous tionof cathode rays is thus received upon a single point, (or as nearly so as possible) of the target. And in this manner I provide a tube which has the' advantage of utilizing alternating currents and giving all the good results of a. direct current tube. The nature of the alternating current used is of small consequence. In the current from an ordinary induction coil there is a certain inverse current, of duration and amplitude depending upon the coil and interrupter construction. My tube does away with the ordinary ill effects of this inverse current b'y utilizing it for production of cathode rays which are directed upon the target.- Whether or not the current in one direction is equal in duration and amplitude to the opposite current, my target is continuously under impact of cathode ways',"as one or the other of the cathodes is always in cathodic action.

Having now described a preferred form 'of my invention, claim:

1. In an X-ray tube or the like, a pair of cathodes and a single target, both of the said cathodes and a single target, both of said cathodes being arranged on one side of the striking plane of said target and focused on a single point thereon, the said striking plane Vbeing determined by a line in the plane of the axes from the two cathodes-through the impact point on the target and at right angles to the bisector of the angle between said axes and by a line at right angles to and intersecting said rst .mentioned line -making an angle of approximately forty-ve degrees with thc'plane of said axes. A In witness that I claim the foregoing I have hereunto subscribed my name.

JAMES E. SEELEY. Witnesses:

JAS. I-I. BALLAGH, JAMES T. BARKELEW. 

